Sync from upstream TF. (#92)

tensorflow/lite/micro/examples/magic_wand/train/requirements.txt

 numpy==1.16.2
-tensorflow==2.5.0
+tensorflow==2.4.0

tensorflow/lite/micro/kernels/BUILD

@@ -342,9 +342,8 @@ cc_library(
     ],
     copts = micro_copts(),
     visibility = [
-        # Needed for micro:op_resolvers but visibility can not be finer-grained
-        # than a package.
-        ":micro_top_level",
+        # Public visibility to allow application code to select kernel variants.
+        "//visibility:public",
     ],
     deps = [
         ":activation_utils",

tensorflow/lite/micro/tools/make/Makefile

@@ -392,6 +392,7 @@ tensorflow/lite/micro/kernels/transpose_conv.cc \
 tensorflow/lite/micro/kernels/unpack.cc \
 tensorflow/lite/micro/kernels/zeros_like.cc
 
+# Load custom kernels.
 include $(MAKEFILE_DIR)/additional_kernels.inc
 
 MICROLITE_TEST_HDRS := \
@@ -686,6 +687,9 @@ include $(MICRO_LITE_EXAMPLE_TESTS)
 # Load the benchmarks.
 include $(MICRO_LITE_BENCHMARKS)
 
+# Load custom kernel tests.
+include $(MAKEFILE_DIR)/additional_tests.inc
+
 # Create rules for downloading third-party dependencies.
 THIRD_PARTY_TARGETS :=
 $(foreach DOWNLOAD,$(THIRD_PARTY_DOWNLOADS),$(eval $(call create_download_rule,$(DOWNLOAD))))
@@ -833,8 +837,6 @@ ifneq ($(findstring $(EXPLICITLY_SPECIFIED_TEST),$(MICROLITE_TEST_SRCS)),)
   $(EXPLICITLY_SPECIFIED_TEST_SRCS),$(EXPLICITLY_SPECIFIED_TEST_HDRS)))
 endif
 
-include $(MAKEFILE_DIR)/additional_tests.inc
-
 # For all the tests that do not have any additional dependencies, we can
 # add a make target in a common way.
 $(foreach TEST_TARGET,$(filter-out tensorflow/lite/micro/kernels/%,$(MICROLITE_TEST_SRCS)),\

tensorflow/lite/micro/tools/make/flatbuffers_download.sh

@@ -91,7 +91,7 @@ if [ -d ${DOWNLOADED_FLATBUFFERS_PATH} ]; then
   echo >&2 "${DOWNLOADED_FLATBUFFERS_PATH} already exists, skipping the download."
 else
   ZIP_PREFIX="dca12522a9f9e37f126ab925fd385c807ab4f84e"
-  FLATBUFFERS_URL="http://mirror.tensorflow.org/github.com/google/flatbuffers/archive/${ZIP_PREFIX}.zip"
+  FLATBUFFERS_URL="https://github.com/google/flatbuffers/archive/${ZIP_PREFIX}.zip"
   FLATBUFFERS_MD5="aa9adc93eb9b33fa1a2a90969e48baee"
 
   TEMPDIR="$(mktemp -d)"